The PIs' long-term objective is to develop and test the effectiveness of biomechanically-based rehabilitation strategies for improving upper extremity function and reducing pain and disability in persons with shoulder pathologies. Rotator cuff pathologies have up to 50% prevalence rates across several populations including persons with spinal cord injury, stroke, occupational exposure to repetitive overhead work, and athletes with repetitive overhead motion exposure. There is increasing evidence linking altered shoulder kinematics with pain and dysfunction in these populations. The altered kinematics is hypothesized to reduce the subacromial space, resulting in impingement of the musculotendinous structures. With sustained or repeated impingement, tissue damage can result, and healing is compromised. The goal of this R03 application is to validate a method to measure the soft tissue geometry and volume of the subacromial space and to establish the relation between this space and tendon pathology. The general hypotheses are that soft tissue data derived from 3D imaging can be accurately registered, and that one can predict when reduction in the subacromial space will generate shoulder pathology. MR scans will be registered to CT scan and bone-fixed motion data from the same subjects. Determination of soft tissue origin/insertion and volume data from imaging data sets will be validated against direct measurement on cadaver shoulders. Additionally, measurement predictions of the location of rotator cuff tissue affected by subacromial reductions during motion will be tested against musculotendinous disease identified operatively. These data will enhance understanding of how rotator cuff tissue is impacted by subacromial space reductions. Addition of soft tissue data will allow for a comprehensive linked data set of precise 3D shoulder complex anatomy and motion across subjects with and without shoulder pathology, and serve as input to enhance existing mathematical shoulder models. This work is novel in its dynamic, comprehensive measurement of the subacromial space, and validation of soft tissue effects with operative data. Subsequent proposals will use these data and derived models to address clinical applications, including design and testing of rehabilitation and surgical interventions through randomized controlled clinical trials. Rotator cuff tendon pathology is the most common of all tendon disorders. The proposed work will improve the understanding of how shoulder movement disorders relate to rotator cuff pathology and provide a foundation for optimizing conservative rehabilitation approaches. Improving cost effective treatment is relevant to public health. [unreadable] [unreadable] [unreadable]